Gas ignition system

ABSTRACT

A gas burner that includes at least one flame aperture is mounted within a burner cone. An electric heating element is mounted close enough to the gas stream which issues from the flame aperture to ignite the gas stream and form a flame. The heating element is also positioned far enough below the aperture so that convection currents will lift the flame above the heating element to minimize flame damage thereto. The ignited flame may be either a main flame or a pilot flame which is directed toward a main flame aperture to ignite the main flame. The gas flow into the gas burner is preferably controlled by a normally closed solenoid-actuated gas valve which is preferably wired in series with the electric heating element to ensure that the electric heating element is energized before the solenoid-actuated gas valve can open.

United States Patent 1 Schantz GAS IGNITION SYSTEM [76] Inventor: Spencer C. Schantz, 16608 W.

Rogers Dr., New Berlin, Wis. 53151 221 Filed: Sept.21,l973 [21] Appl.No.:399,642

[52] US. Cl. 431/263, 317/98 [51] Int. Cl. F23n 7/06 [58] Field of Search 431/258, 263, 66; 317/98 [56] References Cited UNITED STATES PATENTS 3,393,038 7/1968 Burkhalter et a1 431/66 3,600,119 8/1971 Abbott 431/263 X Primary Examiner-Edward G. Favors Attorney, Agent, or Firm-Arthur L. Morsell, Jr.

1 1 Jan.7,l975

[57] ABSTRACT A gas burner that includes at least one flame aperture is mounted within a burner cone. An electric heating element is mounted close enough to the gas stream which issues from the flame aperture to ignite the gas stream and form a flame. The heating element is also positioned far enough below the aperture so that convection currents will lift the flame above the heating element to minimize flame damage thereto. The ignited flame may be either a main flame or a pilot flame which is directed toward a main flame aperture to ignite the main flame. The gas flow into the gas burner is preferably controlled by a normally closed solenoid-actuated gas valve which is preferably wired in series with the electric heating element to ensure that the electric heating element is energized before the solenoid-actuated gas valve can open.

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GAS

zc VALVE /z- SOLENOID GAS IGNITION SYSTEM BACKGROUND OF THE INVENTION This invention relates to gas ignition systems such as used in gas clothes dryers or the like to ignite a gas flame. In the past, such gas ignition systems have been relatively complex and have included temperaturesensing means for measuring the temperature of the ignition heating element to ensure that it was hot enough to light the gas before the gas valve was turned on. The ignition heating element was positioned in the gas stream issuing from the burner and, therefore, was continually exposed to the flame of the burner which reduced the life of the heating element so that it required relatively frequent replacement.

One object of this invention is to provide an improved gas ignition system in which the ignition heating element is so positioned that the flame is lifted away from the heating element by convection currents, thereby minimizing flame damage to the heating element and ensuring longer life therefor.

Another object of this invention is to provide a simple gas ignition system which has built-in safeguards that eliminate the need for complex temperaturemeasuring circuits and the like.

An additional object of this invention is to provide a gas ignition system in which the gas valve can be turned on only when the ignition heating element is conducting electric current so as to be effective to cause ignition of the gas.

A further object of the invention is to provide a gas ignition system in which the electric circuit is so arranged that the ignition heating element heats rapidly due to the starting inrush current for an electric motor.

Other objects and advantages of the invention will be apparent to those skilled in the art from the description which follows.

SUMMARY OF THE INVENTION A gas burner includes structure forming at least one flame aperture from which a stream of inflammable gas may issue. An electric heating element is mounted close enough to the gas flame to ignite the gas and form a flame, but is also positioned far enough below the aperture so that convection currents will lift the flame above the electric heating element, thereby minimizing flame damage to the heating element. The ignited flame may be either a main flame or a pilot flame which is directed toward the main aperture to ignite the main flame. The gas flow into the gas burner is preferably, but not necessarily, controlled by a solenoid-actuated gas valve which is preferably, but not necessarily, coupled in series with the electric heating element to ensure that the heating element is energized before the gas valve can open.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional view of one illustrative gas burner assembly utilizing a gas ignition system of this invention;

FIG. 2 is avertical sectional view of another gas burner assembly utilizing a second gas ignition system of this invention;

FIG. 3 is a vertical sectional view of an additional gas burner assembly utilizing a third embodiment of the invention;

FIG. 4 is an electrical schematic circuit diagram for the gas ignition system illustrated in FIGS. 1, 2, and 3',

FIG. 5 is an enlarged perspective view of one illustrative mounting structure for the electric heating element of this invention; and

FIG. 6 is an enlarged cross-sectional view of a ceramic-coated heating element.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows one illustrative gas ignition system of this invention as used in connection with a burner assembly including a gas conduit 10, a normally-closed solenoid-actuated gas valve 12 connected in series with the gas conduit 10, and a conventional gas mixing chamber 14 in which air, indicated by arrows 16, is entrained and mixes with a stream of gas passing through the chamber 14. The dimensions of the mixing chamber 14 and the dimensions of air openings therefor are selected in accordance with conventional principles to provide a mixture of gas and air that will burn cleanly. This mixture of gas and air enters a burner tube 18 and issues as a mixed gas and air stream from the open end of aperture 20 of burner tube 18.

The end of burner tube 18 is covered by a conventional burner cone 22 to contain the flame therewithin. The illustrated gas burner assembly is of the type that is conventionally used in a clothes dryer which also contains a conventional blower 24 operated by a blower motor 26. The blower 24 draws air through the burner cone 22 as indicated by the arrows 28.

This invention is concerned with an improved gas ig nition system for igniting the mixture of gas and air which issues from the open end 20 of the gas burner tube 18. In accordance with this invention, the flame is lighted by an electric heating element or resistance heater 30 which is mounted on a bracket 32 and is energized from a conventional alternating current electrical source through conductors 34. The electric heating element 30 is positioned so as tO be close enough to the gas stream issuing from the aperture 20 to ignite the gas stream and form a main flame 38, but the electric heating element 30 is also positioned far enough below the aperture 20 so that convection currents caused by the heat of flame 38 will lift the flame 38 above the electric heating element 30 so that the electric heating element 30 will not be exposed to the flame 38 except for the brief initial period when the flame is being ignited. The lifting effect of the convection currents due to the heat of flame 38 is indicated in FIG. I by the upward curl of the flame 38 and by the curved arrow 40.

A baffle may be mounted behind the heating element 30 to provide a pocket of quiet air immediately in front of the aperture 20 to facilitate lighting of the gas stream therefrom. Alternately, the bracket 32 may be enlarged to function as a baffle.

The gas ignition system of this invention may also be used to ignite a pilot flame rather than a main flame, as shown in the embodiment illustrated in FIG. 2, which is the same as the embodiment illustrated in FIG. 1, except for the fact that a small pilot flame nozzle 142 having a pilot flame aperture 144 extends from the bottom of burner tube 118 adjacent to and behind the main flame aperture 120. The parts of this embodiment which are the same as the embodiment of FIG. I are designated by the same number in the series, e.g., the burner tube 118 in FIG. 2 is the same as the burner tube 18 in FIG. 1 the valve 112 in FIG. 2 isthe same as the valve 12 in FIG. 1, and so on.

The pilotflame aperture 144 is located close enough to the main flame aperture 120 so that the pilot flame 146 will extend into the gas stream issuing from main flame aperture 120 and curl up in front of aperture 120 due to the lifting effect of convection currents on pilot flame 146. This causes ignition of main flame 138 after pilot flame 146 is ignited. The pilot flame nozzle 142 is preferably angled downwardly so that pilot flame 146 does not contact the end of burner tube 118. The electric heating element 130 is located so as to'be close enough to the gas stream issuing from pilot flame aperture 144 so as to ignite pilot flame 146, but is located far enough below pilot flame aperture 144 so that pilot flame 146 will be lifted by convection currents above heating element 130 so that pilot flame 146 does not contact heating element 130 except in the brief period during which pilot flame 146 is ignited.

FIG. 3 discloses a third embodiment of the invention which is the same as the embodiment illustrated in FIG. 1 except for a pilot light tube 250 which extends from the back of gas mixing chamber 214 and terminates in a pilot flame aperture 252 adjacent to the main flame aperture 220. The end 254 of pilot light tube 250 is supported in position by extending through openings in bracket 232 and baffle 241. The parts of this embodiment which are the same as the embodiment of FIG. 1 are designated 'by the same number in the 200 series, e.g., the burnerrtube 218 in FIG. 3 is the same as the burner tube 18 in FIG. 1; the valve 212 in FIG. 3 is the same as the burner 12 in FIG. 1; and so on.

The end 254 of pilot light tube 250 is oriented to direct the pilot flame 246 into the gas stream issuing from the main flame aperture 220 to light the main flame 238. Both flames curve upwardly due to the lifting effect of convection currents on the hot'burning gases in the flames. The electric heating element 230 is mounted close enough to the gas stream issuing from pilot aperture 252 to light the pilot flame 246 but is positioned far enough below aperture 252 to enable convection currents t lift pilot flame 246 above heating element 230 to minimize flame damage to heating element 230. v

The life of the above-described electric heating elements 30, 130, and 230 may be extended further by coating the heating element with a suitable ceramic coating 70 as indicated in FIG. 6. The ceramic coating 70 not only prolongs the heater life, but also improves the radiation emission characteristics of the heating element and raises the temperature at which it can be continuously operated. This improves the flame lighting characteristics of the heating element.

All three of the foregoing embodiments of the invention achieve one principal object of the invention which is to minimize flame damage to the ignition heating element. In the past, the ignition heating element has been located in the stream of gas so that the flame constantlyplays upon the heating element and shortens its useful life. In the arrangement of this invention as described above, however, the ignition heating element is protected from flame damage by being positioned so that the flame which is ignited by the heating element will be lifted by convection currents above the heating element, thereby minimizing flame damage.

An additional object of this invention is to provide an improved gas ignition system containing safeguards to assure that the ignition heating element will be energized before the gas valve is opened to ensure that the gas stream will be ignited when it is turned on. To

achieve this objective, the electric heating elements 30, 5 130, or 230 are connected in series with the gas valve solenoid 12, 112, or 212, as shown in FIG. 4. Also connected in series with the gas valve solenoid l2 and the electric heating element 30 are a conventional solenoid-actuated thermostat switch 48, a conventional solenoid-actuated timer switch 50, and a manual off-on switch 52. An overload fuse 54 is also provided in the series circuit, which is coupled acrossa conventional power source 56. The blower motor 26 is preferably coupled in parallel with the gas valve solenoid 12, the thermostat switch 48, and the timer switch 50. Connecting the motor 26 in series with the ignition heating element 30 is preferable because the motor 26, upon starting, draws an initial inrush of current which will cause the heating element 30 to heat rapidly when it is first turned on. The increased current flow through heating element 30 due to motor 26 also enables a larger cross-sectional area to be used for heating element 30, thereby providing a sturdier heating element 30. It should be noted, however, that the safety feature which is attained by connecting the heating element 30 in series with the gas valve solenoid 12 will be obtained whether or not the blower motor 26 is coupled in the circuit as shown in FIG. 3.

Since the positioning of the ignition heating elements 30, 130, or 230 is critical, it is desirable t0 install a safety device which will disable the gas valve solenoid if the heating'element should ever be displaced from its proper position. This is provided as shown in FIGS. 4 and 5 by an electrode or positioning plate 58 which is made of an electrically conductive metal and has a circular opening 60 formed therein. The ignition heating element 30 is mounted by means of stand-off insulators 62 and 64 which are mounted in opening in the bracket 32. The positioning plate 58 is positioned over the heating element 30 in such a position that the heating element 30 is substantially centered in the opening 60 of plate 58. As shown in FIG. 5, positioning plate 58 is supported by a stand-off insulator 66 and has an electrical conductor 68 attached thereto. The electrical conductor 68 is coupled to the side of the power source 56 which is of opposite polarity of the side coupled to fuse 54, as shown in FIG. 3. Accordingly, if the heating element 30 should be displaced from its proper position, it will contact the positioning plate 58 and cause a short circuit which will blow the fuse 54 and disable the entire circuit including the gas valve solenoid 12 and the motor 26 so that neither of these elements can be activated until the short circuit condition is remedied. It will be obvious to those skilled in the art that the dimensions of the opening 50 in the center of positioning plate 58 will be selected to provide the required tolerance limits in the position of the heater element 30. The exterior dimensions of the plate 58 can be preferably sized to contact any conductive foreign bodies to prevent system operation without the heating of element 30. It will be apparent that the value of fuse 54 will be selected to accommodate the normal current flow through heating element 30, including the initial inrush starting current for the motor 26, but will be too small to support the current flowing through a short circuit from heating element 30 to positioning plate 58.

As shown in FIG. 5, cooling fins 72 may be added to conductors 34 and 68 to cool the conductors.

What I claim is:

1. In a flame lighter including an electric circuit, a resistance heater, a gas valve solenoid, and a fuse connected in series with each other across a power source in said circuit, an electrode having an opening therein mounted to surround said resistance heater and make electrical contact therewith if said heating element is moved beyond a predetermined amount or if a conductive foreign body enters the area, said electrode being coupled in said circuit to the side of said power source opposite said fuse, said fuse being of such size as to accommodate the normal current flow through said series circuit but to open if shorting occurs.

2. A flame lighter as defined in claim I and further comprising cooling fins on the conductors coupled to said resistance heater and electrode.

3. In a gas burner having structure forming at least one aperture from which an inflammable gas stream may issue, a flame lighter including an electric heating element positioned sufficiently close to said gas stream as to ignite the gas stream and produce a flame, said electric heating element being also located sufficiently below said aperture that convection currents acting on said flame lift the flame above said electric heating element to minimize flame damage thereto, a normally closed solenoid-actuated gas valve connected in series with said gas burner to control the flow of gas through said apertures, said solenoid-actuated gas valve being electrically coupled in series with said electric heating element to insure that said heating element is energized before said gas valve can open, an additional electrical load connected in parallel with said gas valve, both said gas valve and said additional load being in series with said heating element, thereby increasing current through the heating element to permit a larger crosssectional area to be employed for said heating element with resulting increase in efficiency and durability.

4. The flame lighter of claim 3 in which the additional electric load is a motor which provides rapid initial heating of the electric heating element due to the starting inrush current of the motor.

5. In a gas burner having structure forming at least one aperture from which an inflammable gas stream may issue, a flame lighter including an electric heating element positioned sufficiently close to said gas stream as to ignite the gas stream and produce a flame, said electric heating element being also located sufficiently below said aperture that convection currents acting on said flame lift the flame above said electric heating element to minimize flame damage thereto, a positioning plate which is made of electrically conductive material and has an opening formed therein, an electric circuit, said electric heating element being in said circuit and supported within said opening, a fuse electrically coupled in said circuit in series with said electric heating element, and means in said circuit coupling said positioning plate to the side of said electric heating element opposite said fuse, said fuse being of such size as to carry the normal current flow through said electric heating element but to open in response to the short circuit caused by contact between said electric heating element and said positioning plate.

6. A gas burner defined in claim 5 including a normally closed solenoid-actuated gas valve mechanically connected in series with said gas burner to control the flow of gas through said apertures, said solenoidactuated gas valve being electrically coupled. to said electrical circuit in series with said electric heating element to insure that said heating element is energized before said gas valve can open.

7. A gas burner as claimed in claim 6 in which there is a blower and a blower motor in combination with said gas burner, said blower motor being electrically connected in said electric circuit in series with said electric heating element and in parallel with said solenoid-actuated gas valve.

8. In a gas burner having structure forming at least one aperture from which an inflammable gas stream may issue, an electric circuit, a flame lighter including an electric heating element in said circuit positioned sufficiently close to said gas stream as to ignite the gas stream and produce a flame, said electric heating element being also located sufficiently below said aperture that convection currents acting on said flame lift the flame above said electric heating element to minimize flame damage thereto, a normally closed solenoidactuated gas valve mechanically connected in series with said gas burner to control the flow of gas through said apertures, said solenoid-actuated gas valve being electrically coupled in said electrical circuit in series with said electric heating element to insure that said heating element is energized before said gas valve can open, and a blower and a blower motor utilized in combination with said gas burner, said blower motor being electrically connected in said electric circuit in series with said electric heating element and in parallel with said solenoid-actuated gas valve.

9. In a gas burner having structure forming a main flame aperture from which a main stream of burner gas may issue and also having structure forming a pilot flame aperture from which a pilot stream of gas may issue, a flame lighter including an electric heating element, said electric heating element being positioned sufficiently close to' said pilot flame aperture as to be in the path of unignited gas therefrom during the ignition period to ignite the pilot stream and produce a continuous pilot flame, said electric heating element also being located sufficiently below said pilot flame aperture that convection currents acting on said pilot stream promptly lift the pilot stream above said electric heating element so that the pilot flame will thereafter be clear of the heating element during continued operation thereof to thereby minimize flame damage to the heating element from the continuous operation of the pilot flame.

10. In a gas burner having structure forming at least one aperture from which an inflammable gas stream may issue to provide a continuously operating main burner stream, a flame lighter including an electric heating element, means for continuously energizing said heating element while the main burner stream is operating, said heating element being positioned sufficiently close to said gas stream as to be in the path of unignited gas only during the ignition period to thereby ignite said gas and main burner stream and produce a main flame which is adapted to continue to burn as long as the burner is in operation, said electric heating element being also located sufficiently below said aperture that convection currents acting on said flame promptly lift all flame portions above said electric heating element so that all flame portions will thereafter be clear of the heating element during continued operation of the burner to thereby minimize flame damage to the continuously energized heating element from the continuously operating flame.

a i a: a: 

1. In a flame lighter including an electric circuit, a resistance heater, a gas valve solenoid, and a fuse connected in series with each other across a power source in said circuit, an electrode having an opening therein mounted to surround said resistance heater and make electrical contact therewith if said heating element is moved beyond a predetermined amount or if a conductive foreign body enters the area, said electrode being coupled in said circuit to the side of said power source opposite said fuse, said fuse being of such size as to accommodate the normal current flow through said series circuit but to open if shorting occurs.
 2. A flame lighter as defined in claim 1 and further comprising cooling fins on the conductors coupled to said resistance heater and electrode.
 3. In a gas burner having structure forming at least one aperture from which an inflammable gas stream may issue, a flame lighter including an electric heating element positioned sufficiently close to said gas stream as to ignite the gas stream and produce a flame, said electric heating element being also located sufficiently below said aperture that convection currents acting on said flame lift the flame above said electric heating element to minimize flame damage thereto, a normally closed solenoid-actuated gas valve connected in series with said gas burner to control the flow of gas through said apertures, said solenoid-actuated gas valve being electrically coupled in series with said electric heating element to insure that said heating element is energized before said gas valve can open, an additional electrical load connected in parallel with said gas valve, both said gas valve and said additional load being in series with said heating element, thereby increasing current through the heating element to permit a larger cross-sectional area to be employed for said heating element with resulting increase in efficiency and durability.
 4. The flame lighter of claim 3 in which the additional electric load is a motor which provides rapid initial heating of the electric heating element due to the starting inrush current of the motor.
 5. In a gas burner having structure forming at least one aperture from which an inflammable gas stream may issue, a flame lighter including an electric heating element positioned sufficiently close to said gas stream as to ignite the gas stream and produce a flame, said electric heating element being also located sufficiently below said aperture that convection currents acting on said flame lift the flame above said electric heating element to minimize flame damage thereto, a positioning plate which is made of electrically conductive material and has an opening formed therein, an electric circuit, said electric heating element being in said circuit and supported within said opening, a fuse electrically coupled in said circuit in series with said electric heating element, and means in said circuit coupling said positioning plate to the side of said electric heating element opposite said fuse, said fuse being of such size as to carry the normal current flow through said electric heating element but to open in response to the short circuit caused by contact between said electric heating element and said positioning plate.
 6. A gas burner defined in claim 5 including a normally closed solenoid-actuated gas valve mechanically connected in series with said gas burner to control the flow of gas through said apertures, said solenoid-actuated gas valve being electrically coupled to said electrical circuit in series with said electric heating element to insure that said heating element is energized before said gas valve can open.
 7. A gas burner as claimed in claim 6 in which there is a blower and a blower motor in combination with said gas burner, said blower motor being electrically connected in said electric circuit in series with said electric heating element and in parallel with said solenoid-actuated gas valve.
 8. In a gas burner having structure forming at least one aperture from which an inflammable gas stream may issue, an electric circuit, a flame lighter including an electric heating element in said circuit positioned sufficiently close to said gas stream as to ignite the gas stream and produce a flame, said electric heating element being also located sufficiently below said aperture that convection currents acting on said flame lift the flame above said electric heating element to minimize flame damage thereto, a normally closed solenoid-actuated gas valve mechanically connected in series with said gas burner to control the flow of gas through said apertures, said solenoid-actuated gas valve being electrically coupled in said electrical circuit in series with said electric heating element to insure that said heating element is energized before said gas valve can open, and a blower and a blower motor utilized in combination with said gas burner, said blower motor being electrically connected in said electric circuit in series with said electric heating element and in paralLel with said solenoid-actuated gas valve.
 9. In a gas burner having structure forming a main flame aperture from which a main stream of burner gas may issue and also having structure forming a pilot flame aperture from which a pilot stream of gas may issue, a flame lighter including an electric heating element, said electric heating element being positioned sufficiently close to said pilot flame aperture as to be in the path of unignited gas therefrom during the ignition period to ignite the pilot stream and produce a continuous pilot flame, said electric heating element also being located sufficiently below said pilot flame aperture that convection currents acting on said pilot stream promptly lift the pilot stream above said electric heating element so that the pilot flame will thereafter be clear of the heating element during continued operation thereof to thereby minimize flame damage to the heating element from the continuous operation of the pilot flame.
 10. In a gas burner having structure forming at least one aperture from which an inflammable gas stream may issue to provide a continuously operating main burner stream, a flame lighter including an electric heating element, means for continuously energizing said heating element while the main burner stream is operating, said heating element being positioned sufficiently close to said gas stream as to be in the path of unignited gas only during the ignition period to thereby ignite said gas and main burner stream and produce a main flame which is adapted to continue to burn as long as the burner is in operation, said electric heating element being also located sufficiently below said aperture that convection currents acting on said flame promptly lift all flame portions above said electric heating element so that all flame portions will thereafter be clear of the heating element during continued operation of the burner to thereby minimize flame damage to the continuously energized heating element from the continuously operating flame. 